Adequate methods and containers for the storage of food and other items have long been a concern of human kind. Modern technology advances in storage bag technology have lead to increased utilization of resealable plastic storage bags in the packaging industry as a primary packaging source for a panoply of manufactured or processed goods. Thus, industrial demand for such storage bags continues to expand. A second market exists for these resealable bags, and that market is directed to consumer need for a storage product that can be easily used by the consumer for storing and restoring various items. Thus, on one hand, resealable plastic storage bags form the primary packaging for many products so that the purchasers of the products receive the bag incidentally as the distribution container for the product while, on the other hand, resealable plastic storage bags are purchased as a stand-alone consumer item.
One example of the value of resealable, and therefore reusable, plastic storage bags is found in the food packaging industry. Technological advances, for example in fields of refrigeration and chemical preservation, have generally lead to improvements in the quantity, quality and diversification of food available; such advances contribute significantly in improving health and well-being of persons throughout the world. These advances avoid the necessity of immediate consumption of food items to avoid spoilage; rather, unconsumed food items may be retained and stored for later consumption. This creates a need for suitable storage containers. Accordingly, food packaging technologies have had a role both in the area of initial, i.e. primary, food packaging and the repackaging of food after removal from its original packaging. The present invention concerns both aspects of packaging and food preservation. A wide variety of primary packaging, that is, the original packaging in which the food item sold, is of a type that, once opened, is either unavailable for re-use or is inconvenient for re-use. A need for secondary repackaging naturally occurs where the initial packaging contains a larger quantity of a food item than is required for preparation so that the excess needs to be stored. The need for secondary re-packaging also results, when an excess quantity of a food item has been prepared so that servings thereof remain after a meal. Discarding these "left-overs" wastes the food; therefor, when practical, many persons desire to restore "left-over" both as an economical measure and for convenience for preparing a future meal. Typical containers for re-storage include glass and plastic jars, plastic canisters, flexible plastic wraps, waxed and/or oiled papers, plastic storage bags, and the like. Of these described products for the re-storage of food, one of the most convenient and useful is the plastic storage bag.
Plastic storage bags have found increased popularity in recent times due to the development of closure means which are formed integrally with the storage bag. These intregal closing structures typically are in the form of matable ribs which extend in opposed relation to one another on facing panels that for the bag and adjacent to the mouth of the flexible bag; these ribs may be mated to close the mouth of the storage bag yet separated to open the mouth of the bag thereby accessing the interior either to store an item or to remove an item from the storage bag. Not only are these storage bags convenient for the temporary re-storage of "left-overs" but also these storage bags are useful in the temporary packaging of individualized food portions for transport, for example, for individualized portions of sandwiches and other food items that are included in a home prepared lunch taken to school or to the work place. Further, these re-sealable plastic storage bags are convenient and highly useful to repackage items or food stuff where the same cannot readily be restored in the original packaging once that packaging is opened. Recognizing the value of these recloseable plastic bags, many food processors have implemented such bags as primary packaging for food items distributed to consumers so that the consumer can re-use the initial packaging to restore food portions.
As described more fully in the specification of this application, the common apparatus and method for production of re-sealable plastic storage bags utilizes a extrusion process wherein a continuous tube of plastic material is extruded with the matable ribs being integrally extruded longitudinally on the inside sidewall of the tube. This tube is flattened to engage the mating ribs and the tube is longitudinally slit to create the mouth opening for the storage bags ultimately cut from the continuous tube. This continuous tube is then transversely sealed at spaced longitudinal locations so that storage bags are serially formed adjacent one another out of the tube of material. The storage bags are sequentially cut from the tube and packaged for sale and use.
A disadvantage has long been recognized in the sealed storage bag which results from this manufacturing technique. As a result of engaging the longitudinal sealing ribs, each storage bag which is cut from the continuous tube accordingly has its matable sealing ribs engaged so that the resultant storage bag is closed when packaged. This is highly disadvantageous in an industrial setting wherein these plastic bags are to be used as primary packaging. Due to the fact that the bags are closed, the need to open the bag for insertion of product requires significant time in a production operation. Indeed, where an open recloseable bag is available, packaging labor costs could be reduced by as much as one-third.
On the other hand, where consumer use is the concern, the closed bag presents other problems. When the consumer or other individual uses the storage bag, it is first necessary of course to open the bag by disengaging the sealing ribs prior to insertion of items into the bag. Due to the effectiveness of the above-described bag closure, however, it is sometimes difficult to open the storage bag, for instance when the user's hands are slippery from grease, water or other substances commonly encountered in food preparation environments. Likewise, it is difficult to open these storage bags where the users hands are otherwise occupied. Finally, many elderly people find it difficult to initially open a storage bag which is empty and is in a flattened state due to the inability to readily grip the relatively narrow top margins of the storage bag adjacent the mouth opening; whereas, once a storage bag has items stored therein, it is easier to grip the front and back panels to open the same. Even though the description above has been specifically directed to food packaging and storage, the broader usage of resealable storage bags for primary packaging and secondary restorage experiences similar problems and needs. Accordingly, there is a long felt need for a method and apparatus for producing storage bags that are in an open condition when packaged for use and sale.